Sunday, June 7, 1998 Last modified at 1:34 a.m. on Sunday, June 7, 1998

Kinder, gentler asteroid warnings sought

IRVINE, Calif. (AP) - Following March's false alarm about an asteroid coming dangerously close to Earth in the 21st century and two Hollywood summer blockbusters about cosmic collisions, experts met Saturday to plan asteroid warnings that won't trigger panic.

"Collisions with the Earth is a topic that is so prone to sensationalism that we must be extremely careful about how we communicate new discoveries," said Richard P. Binzel, a planetary science professor at the Massachusetts Institute of Technology. "It took the (March) event to wake us up."

A March 11 report that Asteroid 1997XF11 was headed to within 30,000 miles of Earth's center - and could hit - in October 2028 was front page news and the top story on evening TV news broadcasts.

The report from the International Astronomical Union was quickly debunked by astronomers at NASA's Jet Propulsion Laboratory in Pasadena who recalculated the asteroid's likely path and found it would miss the Earth by 600,000 miles.

"There's a great misperception in the public that for one day there was a possibility that the asteroid would hit in 2028," said Paul W. Chodas, the JPL astronomer whose calculations put those frightened by the report at ease. "According to our calculations, there never was a chance the object would hit the Earth."

In the aftermath, scientists began thinking about how they could avert another scare, although efforts to delay release of data could be difficult given the increasingly free flow of scientific information via Internet.

Since that time, Hollywood has put killer asteroids and comets into the public mind with the "Deep Impact" and "Armageddon," as well as made-for-TV movies earlier this year.

In light of the heightened awareness, the National Research Council's Committee on Planetary and Lunar Exploration brought together astronomers who identify and track asteroids, experts in risk management, seismologists with experience in earthquake and volcano warnings and reporters.

The main problem in reporting new asteroid discoveries is that only a fraction that initially seem potentially hazardous turn out to be headed close to Earth once scientists refine orbital calculations.

"It is extremely unlikely that we're going to have an asteroid come with a real possibility of a collision," Chodas said, adding that 15 minutes after he had the XF11 data in hand, his calculations found "zero threat."

In April, the National Aeronautics and Space Administration drafted "Interim Roles and Responsibilities for Reporting Potentially Hazardous Objects," which recommends consultation and coordination among experts before any public announcements. It might take up to 48 hours for experts to consult with each other, Chodas said. NASA wants an additional 24 hours before the information is released.

Chodas, who computes orbits for asteroids and comets, went into the meeting with an open mind about giving NASA the extra 24 hours, although he wondered what the agency planned to do during that time.

An earthquake expert urged openness about any potential threat, as long as the uncertainty of initial observations is clearly explained.

"You can't control the flow of news but you can be as truthful as possible up front," said Alan Lindh of the U.S. Geological Survey. "The press, public and public officials seem to deal well with uncertainty, but they don't deal well with the suggestion you might hold out on them."

Binzel, who opposes mandating a set waiting period, suggested that NASA or the International Astronomical Union establish a code of conduct under which amateur or professional astronomers would seek verification from colleagues before going public.

Without that, false alarms will create "total loss of credibility among the astronomers."

Scientists have so far identified 123 potentially hazardous asteroids that could pass within 5 million miles of Earth. They've discovered 200 of the estimated 2,000 large asteroids that could pass within 30 million miles of Earth.

NASA is spending more money in the next decade to scan space for others.

One of the giant rocky chunks is thought to have slammed into Mexico's Yucatan Peninsula 65 million years ago, wiping out dinosaurs and most species.

Scientists know that in 1908, an asteroid exploded over Siberia, flattening nearly 1,000 square miles of forest.

Harry Y. "Hap" McSween, the University of Tennessee geologist who chaired the daylong workshop, said it was important that the event was getting U.S. scientists talking, but added that "this is going to have to be an international discussion."